Being the perfectionist that I am, it really bothers me that my cake was so crappy.  After thinking about it all night, all morning, in spinning class, and then consulting the recipe again - this is what I did wrong:

1. i used baking powder and not baking soda!  i think this may have been my biggest mistake.
2. i had my buttermilk and milk mixed up.  I used 1/3 cup of milk before I realized my mistake.
3. I used 3.5 cups of cake flour, it called for 3 1/3.
4. I only had 1 ounce of red food coloring - the recipe called for 3.

I am baking a new cake today and I have faith that it will be as light and fluffy and delicious as it should be.  hopefully it will be delicious enough to warrant a picture!